diff options
author | Michael Kerrisk <mtk.manpages@gmail.com> | 2015-01-16 20:28:06 +0100 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2015-01-19 12:05:32 +0100 |
commit | 996636ddae5cab8883bd76b996cd4f2ea9a152be (patch) | |
tree | e9751130d04210fa6e938f29c088b89754ecd7df /kernel/sys.c | |
parent | 40a35503401a5a5ffd8bb03b120724e213160584 (diff) | |
download | linux-996636ddae5cab8883bd76b996cd4f2ea9a152be.tar.bz2 |
futex: Fix argument handling in futex_lock_pi() calls
This patch fixes two separate buglets in calls to futex_lock_pi():
* Eliminate unused 'detect' argument
* Change unused 'timeout' argument of FUTEX_TRYLOCK_PI to NULL
The 'detect' argument of futex_lock_pi() seems never to have been
used (when it was included with the initial PI mutex implementation
in Linux 2.6.18, all checks against its value were disabled by
ANDing against 0 (i.e., if (detect... && 0)), and with
commit 778e9a9c3e7193ea9f434f382947155ffb59c755, any mention of
this argument in futex_lock_pi() went way altogether. Its presence
now serves only to confuse readers of the code, by giving the
impression that the futex() FUTEX_LOCK_PI operation actually does
use the 'val' argument. This patch removes the argument.
The futex_lock_pi() call that corresponds to FUTEX_TRYLOCK_PI includes
'timeout' as one of its arguments. This misleads the reader into thinking
that the FUTEX_TRYLOCK_PI operation does employ timeouts for some sensible
purpose; but it does not. Indeed, it cannot, because the checks at the
start of sys_futex() exclude FUTEX_TRYLOCK_PI from the set of operations
that do copy_from_user() on the timeout argument. So, in the
FUTEX_TRYLOCK_PI futex_lock_pi() call it would be simplest to change
'timeout' to 'NULL'. This patch does that.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Darren Hart <darren@dvhart.com>
Link: http://lkml.kernel.org/r/54B96646.8010200@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/sys.c')
0 files changed, 0 insertions, 0 deletions